Effects of soybean genotype on the glyceollin elicitation competency of cotyledon tissues to Phytophthora sojae glucan elicitors

In some soybean cultivars, wounding or hypersensitive (HR) cell death is re quired for the activation of the competency of immediately surrounding (pro ximal) cells to deploy defense responses to the cell wall glucan elicitor f rom the pathogen Phytophythora sojae. These proximal defense responses incl ude Phenolic polymer deposition and accumulation of the glyceollin phytoale xins. In Williams soybeans, elicitation competency is an induced and transi ent state and is triggered by two endogenous competency factors Which are a ssociated with wounded or HR dying cells. In this paper it is reported for the first time that certain cultivars. including Harosoy and Bragg, are at least partially inherently competent. That is, they do not require wound- o r HR-associated factors for the glyceollin response to occur. The effects o il competency of several Rps genes for resistance to P. sojae are examined in near isolines of both Williams (incompetent) and Harosoy (competent) and genes controlling nodulation by Bradyrhizobium. Preliminary results sugges t that genes that are linked to the Rp 1,3 and 7 loci may modulate the sign aling events required for the establishment of the competent state. (C) 200 1 Academic Press.